Disarm the anti-theft system on your 2003 Mustang.
The alarm should shut off automatically. If it does not, continue to step 2.2. Press the panic button on the wireless transmitter to shut down the anti-theft alarm.
Instructions
1. Wait 30 seconds for the alarm to stop and three minutes for the lights to stop flashing.Many Ford vehicles come with an anti-theft deterrent alarm system to protect the car. The anti-theft alarm is engaged when someone tries to break into the car or when you press the panic button on the wireless transmitter. When this happens, the headlights will flash repeatedly and the Mustang will make loud siren noises to alert bystanders and scare off thieves. There are multiple ways to turn the alarm off should you accidentally set off the anti-theft system.
3. Unlock the Mustang car door and put the key into the ignition, then turn the engine on. The alarm anti-theft system will shut down and go into disarmed mode.
